BACKGROUNDPulmonary mucosa-associated lymphoid tissue (MALT) lymphoma is the most frequent type of non-Hodgkin's lymphoma (NHL) that primarily involves the lungs. It represents a rare entity accounting for less than 1% of all NHLs and the clinical features have yet to be clearly elucidated.

METHODSThe clinicopathological features and radiological data of 23 patients with pulmonary MALT lymphoma confirmed by biopsy in Peking Union Medical College Hospital from January 2001 to December 2010 were retrospectively analyzed.

RESULTSAt diagnosis, there were 15 women and 8 men. The median age was 55.1 years (range, 37 - 73 years). One patient had a history of primary Sjoren's syndrome, another patient had a history of systemic lupus erythematosus (SLE) and secondary Sjoren's syndrome. One patient had a history of previous hematological malignancy (lymphomatoid papulosis in complete remission). In addition, one patient had simultaneous gastric and pulmonary involvement and one patient had simultaneous parotid gland and pulmonary involvement. The other 21 patients had disease localized within the lungs at the initial diagnosis. Among them, 10 patients were asymptomatic while two had non-specific pulmonary symptoms. There were six patients with fever, four patients had low grade fever and two patients had moderate-high fever. The most common manifestations were cough (n = 10), expectoration (n = 8), exertional dyspnea (n = 8), fatigue (n = 7), body weight loss (n = 6) and crackles (n = 6). Blood tests showed low to moderate anemia in six cases, elevated erythrocyte semimentation rate (ESR) in 10 cases and only one patient had elevated lactate dehydrogenase (LDH). High resolution computed tomography (HRCT) of the chest revealed bilateral disease in 13 patients, air space consolidation with or without air bronchogram in 15 patients, lung nodules in 15 patients, patchy opacities in eight patients, lung mass in three patients and pleural effusion in five patients. Flexible fiberoptic bronchoscopy showed multiple nodules in five patients and almost normal morphology in 18 patients. Pathological diagnosis was obtained by bronchial biopsies in three cases, by CT-guided percutaneous lung biopsies in 11 cases and by surgical biopsies in nine cases. Of the 23 patients, one remained untreated, while 22 received various combinations of treatment (surgery alone in three patients, surgery plus chemotherapy in six patients, and chemotherapy alone in 13 patients). Twenty-one patients remained alive during the median follow-up of 23 (0.25 - 84) months, while one patient died from unknown causes, one patient died from lung infection.

CONCLUSIONSPulmonary MALT lymphoma tends to occur in old-aged females and to be limited to the lungs on the initial diagnosis and LDH's level was normal in most patients. Lung nodules, patchy opacities and air space consolidation were the main HRCT manifestations. Association with immunohistochemical studies, CT-guided percutaneous lung biopsies and surgical biopsies were helpful to the diagnosis. Prognosis for this lymphoma tends to be indolent.